The present invention relates to a board connection structure that mutually connects multiple circuit boards that are arranged in layers, an electronic device equipped with the board connection structure, and a connector used in the board connection structure.
Multiple circuit boards on which various circuit elements are mounted, are arranged in layers in audiovisual equipment, computers, and other electronic devices. Arranging multiple circuit boards in this laminated way improves efficiency with which components are packed inside such electronic devices and makes them smaller.
In making electrical connections between the conductive parts on circuit boards where multiple circuit boards are arranged in layers, so-called board-to-board connectors have been employed, in which a plug is provided on one circuit board, a receptacle is provided on another circuit board, and the plug and receptacle are joined by a direct mechanical connection (Japanese patent application Laid-Open No. 59-148289, 1984).
However, in such conventional board connection structure, the relative position of two circuit boards is uniquely determined by the mechanical connection between the plug and the receptacle because of rigidity of the boards themselves. Thus if positional displacement of two circuit boards is set smaller in order to improve their packability inside the housing of an electronic device, the problem arises that one must attach the plug and receptacle precisely positioned on each circuit board. In particular, as electronic devices are given more sophisticated functions to perform and circuit boards are made larger, the precision with which plugs and receptacles are attached to circuit boards greatly affects the positional displacement of the circuit boards they connect.
Since the plug and the receptacle are fitted together mechanically by making the connection with such a board-to-board connector, it is difficult to adjust the distance between laminated circuit boards to fit the dimensions of the housing of the electronic device, which puts limits on how small the electronic device may be made. A further problem is that in connecting together the circuit boards with such board-to-board connector, the plug and the receptacle must be fitted together while checking them from the side, which makes the assembly work more complicated during manufacturing.
It is an object of this invention to provide, in a board connection structure by which electrical connection is made between the conductive parts of multiple circuit boards arranged in layers, a board connection structure that reduces a positional displacement between the two circuit boards without considering the positioning precision of the connectors provided on each circuit board, to provide an electronic device that can be made smaller by reducing the positional displacement of circuit boards, and to provide a connector that makes it easy to connect multiple circuit boards.
In order to achieve the above objects, a board connection structure of the present invention is a board connection structure in which conductive parts of at least two circuit boards arranged in layers are electrically connected. The board connection structure includes a pair of connectors having electrical continuity with the conductive parts of the circuit boards arranged facing each other, and a flexible wiring board that is electrically connected to each of the connectors of the pair and ensures electrical continuity between said pair of connectors. The connector is arranged such that inserting said flexible wiring board therebetween ensures an electrical connection and a physical anchoring in the structure.
Here, one can use as a connector a so-called non-ZIF (non-zero insert force) type. For example, one can use a connector that has a non-conductive case in which an opening is formed into which a flexible wiring board is inserted, and a metal contact part which is provided inside the case, is formed on the flexible wiring board has a claw part for resisting the pullout force of the inserted flexible wiring board.
As the flexible wiring board one can use the board on which FFC (flat flex cable) or other electrodes are formed on the front surface and/or back surface of the flexible board made of PET (polyethylene terephthalate), etc.
With the present invention, a pair of connectors are connected via the flexible wiring board, making it possible to absorb the shift of mounting position of connectors on a circuit board and to house electronic devices in a housing with reduced positional displacement of the circuit boards.
Connection via the flexible wiring board makes it possible to adjust the distance between the two circuit boards, thereby making it possible to reduce the size of electronic devices using the board connection structure of this invention.
Since the physical anchoring between the two circuit boards is ensured just by inserting the flexible wiring board into the connector, the two circuit boards can be connected simply, just by inserting a flexible wiring board into the connector, which simplifies the assembly work of connecting the circuit boards together.
Also, because the connector has the claw part that resists the pulling-out force of the flexible wiring board, a board connection structure can be provided, in which insertion is easy, and it is difficult to break the connection between the connector and the flexible wiring board.
In addition, because the flexible wiring board is provided with electrodes formed on the front surface and/or back surface of a flexible board material, it is easy to manufacture flexible wiring boards using conventional wiring pattern printing, etc.
It is desirable that at least one of the aforesaid pair of connectors be a through-type connector that the flexible wiring board pierces, and that on the circuit board surface on which this through-type connector is provided, there would be formed holes into which the flexible wiring board can be inserted from the surface opposite the mounting surface of the through-type connector.
The board connection structure of the present invention can be made by a procedure such as the following:
(1) Attach a flexible wiring board to the connector mounted on the circuit board arranged at the bottom of the multiple laminated wiring boards.
(2) Insert the end of the flexible wiring board into the through-type connector provided on the laminating circuit board, pull the end of the flexible wiring board out through the pullout opening of the through-type connector and the hole in the circuit board, adjust the distance between the two circuit boards, and arrange the circuit board in optimum position. If laminating three or more circuit boards, laminate a circuit board on which through-type connectors are mounted and on which holes are formed into the flexible wiring board can be inserted, and repeat the operation of step (2).
That is, by the board connection structure of this invention, adopting a composition such as proposed in this application, circuit boards can be connected without checking from the side, which greatly reduces the assembly work during manufacturing.
Also, the electronic device of this invention is characterized in that it can have any of the aforesaid board connection structures.
The electronic device could be a notebook-type personal computer, an audiovisual device, a computer game machine, etc.
By adopting the board connection structure of the present invention, the positional displacement of laminated circuit boards can be reduced, which improves the packability of the electronic device into a housing and makes it easy to reduce the size of the electronic device. And because the work of connecting boards can be done without checking from the side, the work of assembling the electronic device can be greatly reduced.
Also, the connector of the present invention has an insertion opening into which the flexible wiring board is inserted and a pullout opening through which the flexible wiring board inserted through this insertion opening, is pulled out. It can go through the flexible wiring board.
The connector of this invention preferably ensures electrical connection and physical anchoring just by inserting the flexible wiring board.
With such a connector, by forming insertion holes for flexible wiring boards in multiple circuit boards arranged in layers and allowing the flexible wiring board to go through the connector, multiple circuit boards can be electrically connected to each other, which can greatly reduce the work of connecting the circuit boards.
A sloping surface may be formed around the insertion opening of the connector to guide in the flexible wiring board.
That is, by forming such sloping surface, the flexible wiring board is guided quickly into the inside of the connector, which makes the work of connecting the circuit boards even easier.